Magnetostrictive testing with wireless transmitter(s) and remote receiver(s)

Abstract

A method of magnetostrictive (MS) guided wave testing of a ferromagnetic structure. One or more MS transmitters, each configured as a patch of ferromagnetic material, are acoustically coupled to the structure. Each MS transmitter is magnetized to produce a bias magnetic field in the patch. One or more MS receivers are acoustically coupled to the structure in a location remote from the MS transmitter(s). An alternating current (AC) is applied to the structure, thereby producing time-varying magnetic fields and MS vibrations in the MS transmitter(s) resulting in guided waves in the structure. MS response signals are received at the MS receiver(s), indicating whether the structure has any anomalies.

What is claimed is: 
     
       1. A method of magnetostrictive (MS) guided wave testing of a ferromagnetic structure, comprising:
 providing one or more MS transmitters, each configured as a patch of ferromagnetic material; 
 magnetizing the one or more MS transmitters to produce a bias magnetic field in the patch; 
 acoustically coupling the one or more MS transmitters to the structure; 
 acoustically coupling one or more MS receivers to the structure in a location remote from the MS transmitter; 
 using an alternating current (AC) source to apply an AC current to the structure at a location remote from the one or more MS transmitters, thereby producing time-varying magnetic fields and MS vibrations in the one or more MS transmitters resulting in guided waves in the structure; 
 wherein the applying step is performed without electrical coupling between the AC source and the one or more MS transmitters other than through the structure; and 
 receiving MS signals at the one or more MS receivers. 
 
     
     
       2. The method of  claim 1  wherein the magnetizing step is performed such that the one or more MS transmitters produce transverse guided waves. 
     
     
       3. The method of  claim 1  wherein the magnetizing step is performed such that the one or more MS transmitters produce longitudinal guided waves. 
     
     
       4. The method of  claim 3  wherein the magnetizing step is performed such that the one or more MS transmitters are magnetized parallel to the time-varying magnetic fields. 
     
     
       5. The method of  claim 3  wherein the magnetizing step is performed such that the one or more MS transmitters are magnetized through their thickness. 
     
     
       6. The method of  claim 1 , wherein the magnetizing step is performed with permanent magnets, residual magnetization, or an external magnetic field. 
     
     
       7. A magnetostrictive (MS) guided wave test system for monitoring a ferromagnetic structure, comprising:
 one or more MS transmitters, each configured as a patch of ferromagnetic material that is acoustically coupled to the structure; 
 wherein the one or more MS transmitters are magnetized to produce a bias magnetic field in the patch; 
 one or more MS receivers acoustically coupled to the structure in a location remote from the MS transmitter; 
 an MS instrument operable to apply alternating current (AC) to the structure at a location remote from the one or more MS transmitters, thereby producing time-varying magnetic fields and MS vibrations in the one or more MS transmitters resulting in guided waves in the structure; and further operable to receive MS signals from the one or more MS receivers; 
 wherein the MS instrument has an AC source with electrical connection to the structure such that the time-varying magnetic field is produced without electrical coupling between the AC source and the one or more MS transmitters other than through the structure. 
 
     
     
       8. The system of  claim 7  wherein at least one of the one or more MS transmitters is magnetized to produce transverse guided waves. 
     
     
       9. The system of  claim 7  wherein at least one of the one or more MS transmitters is magnetized to produce longitudinal guided waves. 
     
     
       10. The system of  claim 9  wherein the least one of the one or more MS transmitters is magnetized parallel to the time-varying magnetic fields. 
     
     
       11. The system of  claim 9  wherein the least one of the one or more MS transmitters is magnetized through its thickness. 
     
     
       12. The method of  claim 9  wherein the one or more MS transmitters are magnetized with permanent magnets, residual magnetization, or an external magnetic field. 
     
     
       13. The system of  claim 7  wherein the MS instrument operates in a pulser-receiver mode for one-way guided wave testing. 
     
     
       14. The system of  claim 7  wherein the MS instrument operates in a pulse-echo mode for two-way guided wave testing.